I suffered greatly from anxiety and panicking. I uses to think that my heart rate was extremely fast. But being hooked up on a monitor, when I felt it was over 100. But looking at the monitor, it was in the 80s.
Our hearts beat fast, slow, fast slow throughout the day and night. If you regularly exercise and eat well. Be sure that your body will treat you well.
And even if something might happen, why worry about it? If it's going to happen, it's will hapoen, rather you worry about it or not.
It's best to just live well, treat yourself and others well, and enjoy your life. We didn't bring ourselves into this world. And, unless we our depressed enough to end things; we can't prevent ourselves from leaving here.
Ultimately, if it's time to go, we will go.
So why worry about it? I had to come to that conclusion for myself, because I deal with anxiety and panicking. After my brother spent a month and a half, on life support, and passed. I watched that 38yo man die, and there was nothing we could do to stop it.
He really was too young to go. And he definitely didn't want to go. But it was surely his time to go. We have to learn to be at peace with ourselves, others, and most definitely, our Maker. Let tomorrow worry about itself, and just live each moment to its fullest.
By the way: from an axiety sufferer, to another. What you are describing sounds like aniexty and panic disorder to me.
The brain can cause a whole lot of havoc on our bodies if we let it. Just try no to be a self fulfilled prophecy there.
Take good care of yourself